1. Field of the Invention
The present invention relates to a method and an apparatus for assembling a photo film cassette. More particularly, the present invention relates to a method and an apparatus for assembling a photo film cassette with increased productivity.
2. Description of the Related Art
There is a known photo film cassette as disclosed in U.S. Pat. Nos. 4,834,306 and 4,846,418 and a commonly assigned U.S. Pat. No. 5,271,577 (corresponding to JP-A 3-37645), in which a cassette shell is molded from resin, and in which rotation of a spool causes a leader of a photo film strip to advance to an outside of the cassette shell (hereinafter referred to as leader-advancing cassette). Unlike the most available, earlier type of photo film cassette, the leader of the leader-advancing cassette is fully contained in the cassette both before and after exposure of the photo film strip. It is thus possible to increase the light-tightness of the cassette for protection of the photo film strip, and to facilitate handling of the cassette.
There is a commonly assigned co-pending U.S. patent application Ser. No. 08/091,626 (corresponding to EP 0 582 852 A1, and JP-A 6-35123) disclosing a cassette assembling apparatus. Cassettes with a spool are prepared in a bright room, and set in the assembling apparatus one after another. A guide plate of a tongue shape is inserted into a film passageway of the cassette. A trailer of a photo film strip is slid in contact with the guide plate, inserted into the cassette, and retained on the spool. Then the spool is rotated to wind the photo film into the cassette.
In this assembling apparatus, only one cassette can be set at one time. This is unsuitable for mass production of photo film cassettes.
There is a known system for producing a photo film cassette: a photo film is cut to have a predetermined length and is wound on a spool, and loaded with a photo film cassette. The cassette producing system includes a cutting apparatus and a loader apparatus. The cutting apparatus produces the photo film strip at the length associated with the available maximum number of frames. The loader apparatus retains the photo film strip on the spool, and rotates the spool for the loading of the photo film strip. There is a prior document JP-A 4-80161 disclosing delivery of photo film strips toward a number of loader apparatuses: one cutting apparatus is followed by the plural loader apparatuses, and associated with a delivering mechanism, through which the photo film strips are delivered for positions of the receipt at the loader apparatuses, to make effective use of performance of the cutting apparatus and with suitability to a supply speed of photo film strips.
In such manufacturing systems, photo film strips are delivered by a changeover gate toward two loader apparatuses for loading the cassette with the photo film strips. One of the loader apparatuses winds a photo film strip around a spool, while the other loader apparatus receives another photo film strip to stand by for the loading to increase efficiency in manufacturing photo film cassettes.
In this cassette producing system, there is a considerable distance between the changeover gate and an entrance of a transport path of the loader apparatuses. The photo film strip passing the section having this distance is not sufficiently regulated in orientation and position. There is a problem in that a curling tendency of the photo film strip may hinder the photo film strip from being received by any of the transport paths of the loader apparatus. It is also likely that a photo film strip may be accidentally bent due to a delivering angle during conveyance. Friction to the photo film strip during the conveyance may create scratches on it.
To drive a gate for changing over, it can be conceived to use an air cylinder or cam, with which, however, it is impossible at high speed to deliver photo film strips toward positions as desired. The low speed of such conventional drive structures for changing over results in low efficiency in manufacturing photo film cassettes. Only limited positions for receiving the delivery can be determined when the air cylinder or cam is used. It is extremely difficult to increase the number of the loader apparatuses to be set up, in other words, the number of the positions for receiving delivery. These obstacles reduce the productivity of manufacturing photo film cassettes.